I would agree. You are asking a lot to run most games on 3 displays from a GTX660. I don't think I'd run triple monitors in game unless I was running some sort of SLI setup or at a minimum a top tier card.
Also, consider a GTX760 instead of a GTX660. The cards you listed are factory OCed cards and will carry a premium. That premium price will almost land you a new gen card that will perform better. The only GTX660 I could suggest right now is a very good deal on one around $150-$170. My co worked landed a GTX760 on Newegg for $200 on a holiday deal.